Help where I can!!
Epsum
1. Oil viscocity is relative to temperature to a certain level. As oil gets hotter it starts to thin. When oil is very cold it is very thick. This is because heating the oil (or adding heat energy) excites the atoms and makes it easier for them to slide over each other disassociating and reassociating themselves in the process. Cold oil has lost heat energy so therefore becomes more viscous and not willing to move because it doesn't have much energy (in the form of heat).
2. Magnetic circuit breakers - All I can about resetting circuit breakers is to only do it once. It is possible for certain systems to draw a spike of electrical energy and therfore pop a breaker. Once reset if it continues to pop then leave it and assume a fault. COntinued resetting can cause a fire in extreme cercumstances.
3. Carb heat effects the mixture indirectly because when carb heat is selected outside air is usually directed over the exhaust shroud and the sent into the intake at a higher temperature. When air is heated it becomes less dense (think convection currents and why air pockets rise and Meterology). Because a given unit of air is now less dense it contains less air. If the fuel flow remains the same and the unit of air is less then the mixture will be rich because there will an excess of fuel in the combustion cycle. This extra fuel also contributes to the cooling of the engine because it takes latent heat from the cylinder walls and passes out of the exhaust - taking a small amount of heat energy with it.
4. This is indeed the case of being aircraft specific. Most systems will indicate that the gear is down and locked and will not have a sensor for the state of the doors. However more complex systems will have sensors for the doors also.
Hope this helps
The Reverand